Make s3upload function return the UUID

Generating the UUID can be can be contained within this function,
thus any other part of the code using it doesn’t have to do the
ID-generating stuff itself.

app/main/uploader.py

@@ -1,3 +1,4 @@
+import uuid
 import botocore
 from boto3 import resource
 from flask import current_app
@@ -5,7 +6,7 @@ from flask import current_app
 FILE_LOCATION_STRUCTURE = 'service-{}-notify/{}.csv'
 
 
-def s3upload(upload_id, service_id, filedata, region):
+def s3upload(service_id, filedata, region):
     s3 = resource('s3')
     bucket_name = current_app.config['CSV_UPLOAD_BUCKET_NAME']
     contents = filedata['data']
@@ -27,10 +28,13 @@ def s3upload(upload_id, service_id, filedata, region):
         s3.create_bucket(Bucket=bucket_name,
                          CreateBucketConfiguration={'LocationConstraint': region})
 
+    upload_id = str(uuid.uuid4())
     upload_file_name = FILE_LOCATION_STRUCTURE.format(service_id, upload_id)
     key = s3.Object(bucket_name, upload_file_name)
     key.put(Body=contents, ServerSideEncryption='AES256')
 
+    return upload_id
+
 
 def s3download(service_id, upload_id):
     contents = ''

app/main/views/send.py

@@ -110,9 +110,7 @@ def send_messages(service_id, template_id):
     form = CsvUploadForm()
     if form.validate_on_submit():
         try:
-            upload_id = str(uuid.uuid4())
-            s3upload(
-                upload_id,
+            upload_id = s3upload(
                 service_id,
                 Spreadsheet.from_file(form.file.data.filename, form.file.data).as_dict,
                 current_app.config['AWS_REGION']
@@ -161,6 +159,8 @@ def get_example_csv(service_id, template_id):
 @user_has_permissions('send_texts', 'send_emails', 'send_letters')
 def send_test(service_id, template_id):
 
+    file_name = 'Test message'
+
     template = Template(
         service_api_client.get_service_template(service_id, template_id)['data'],
         prefix=current_service['name']
@@ -173,13 +173,18 @@ def send_test(service_id, template_id):
                 [first_column_heading[template.template_type]] + list(template.placeholders),
                 get_example_csv_rows(template, use_example_as_example=False, submitted_fields=request.form)
             ])
-            filedata = {
-                'file_name': 'Test message',
-                'data': output.getvalue()
+            upload_id = s3upload(
+                service_id,
+                {
+                    'file_name': file_name,
+                    'data': output.getvalue()
+                },
+                current_app.config['AWS_REGION']
+            )
+            session['upload_data'] = {
+                "template_id": template_id,
+                "original_file_name": file_name
             }
-            upload_id = str(uuid.uuid4())
-            s3upload(upload_id, service_id, filedata, current_app.config['AWS_REGION'])
-            session['upload_data'] = {"template_id": template_id, "original_file_name": filedata['file_name']}
             return redirect(url_for(
                 '.check_messages',
                 upload_id=upload_id,